Field of the Invention
The present invention relates to a thermoelectric module apparatus, and more particularly, to a thermoelectric module apparatus that includes: a pipe-shaped housing having a hole that is longitudinally formed; a thermoelectric module coupled to the housing; and heat sinks combined with the thermoelectric module, in which the pipe-shaped housing has a plurality of mount holes having predetermined width and length, longitudinally extending, and arranged circumferentially in parallel with each other, the thermoelectric module has a plurality of thermoelectric plates having predetermined width, length, and thickness, the housing is connected to first sides in the width direction of the thermoelectric plates, the thermoelectric plates are disposed in the mount holes respectively with a portion in the width direction inserted and exposed inside the hole as much as a predetermined width and a portion in the width direction protruding and exposed outside the housing as much as a predetermined width, and the heat sinks are connected to the portions exposed outside the housing.
Description of the Related Art
An internal combustion engine generates power by burning specific fuel. In this process, a large amount of waste heat is produced, and particularly, a large amount of waste heat is included in an exhaust gas discharged through an exhaust pipe.
A thermoelectric element is a device that generates electricity, using a temperature difference, and when electricity is generated using waste heat, energy can be recycled and energy efficiency of an internal combustion engine can be improved.
However, it is an important problem to increase energy generation efficiency by increasing the temperature difference between a hot side and a cold side of thermoelectric elements.
It is very important to study high-efficiency thermoelectric active materials in the thermoelectric field. A property of a thermoelectric material, so-called figure of merit is expressed by ZT.
  ZT  =                              S          2                ⁢        σ            k        ⁢    T  
In this equation, Z is figure of merit of a thermoelectric material, S is seebeck coefficient, σ is electric conductivity, k is thermal conductivity, and T is temperature. In order to achieve high figure of merit, high seebeck coefficient and electric conductivity and low thermal conductivity are required. Since the thermal conductivity follows Wiedemann-Franz law, so it is difficult to control independently from the electric conductivity, but it is possible to decrease the entire thermal conductivity by controlling the nano-structure of a material.
Since Bi2Te3 has been discovered as a thermoelectric material, the maximum ZT remains now at about 1. When ZT is larger than 2, a thermoelectric system may concur with a common technology of, for example, temperature control. The use and application of thermoelectrics depend directly on the parameter, ZT, and when a thermoelectric element is formed in a module, the following efficiency equation is obtained.
  η  =                    Δ        ⁢                                  ⁢        T                    T        h              ·                                        1            +            ZT                          -        1                                          1            +            ZT                          ·                              T            c                                T            h                              
In this equation, ZT is a property of a thermoelectric material, ΔT is Th−Tc, Th is at the temperature of a hot side, at a portion being in contact with an exhaust pipe and Tc is the temperature of a cold side, at a portion attached to a heat sink.
As can seen from the equation, even if there is a difference of 1° C. or more between Th and Tc, a thermoelectric module generates electric energy, and the larger the difference between Th and Tc, the larger the efficiency. For example, for ZT=1, ΔT=50° C., Th′=100° C., and Tc=50° C.,
  η  -            50      100        ·                                        1            +            1                          -        1                                          1            +            1                          +                  50          100                      -  0.10819  -      about    ⁢                  ⁢    10.82    ⁢    %  
Efficiency of about 10.82% is achieved, and when the number of flexible thermoelectric modules increases, more electric energy will be generated.
However, when the temperature of the hot side increases, the efficiency decreases in the equation, so it is required to increase the temperature difference between the cold side and the hot side as much as the increase in temperature of the hot side.